He really incarnates the spirit of Slytherin, in a way. Ambitious, manipulative, preferring to pull the strings from the shadows instead of taking risks in the limelight. But unlike nearly everybody else in Slytherin (which is a big mistake on Rowling's part imho, but we'll get to that in due time, end of book seven), he's not on the evil side. He evidently has some remains of prejudice against Muggleborns, but isn't really set against them - kind of like how older people back in the day had this slightly dubious yet not really malevolently racist view of black people.

What's remarkable is that he has been on the run for a year, he says. So he must have expected Voldemort would try to recruit him long before Voldemort gave up his secrecy... interesting.

Manipulative isn't necessarily evil. Dumbledore plays dirty, perhaps, but Slughorn is old and wise enough to know he's being played, and takes the bait anyway. The choice is his. So I don't think Dumbledore is to blame here.

I don't know about trying really hard. The female Weasleys (which might as well include Hermione) are too hard on her, yes, but it's not as if she's entirely innocent in the matter. Fleur *is* arrogant, but then she has every reason to be, and she has a good heart. I imagine her attitude towards Bill's family isn't meant to be as rude as it ends up coming across, but she probably could have done more effort if she had bothered.

I'm not sure if we're really meant to infer here that Mrs. Weasley, Ginny and Hermione are really wrong with their initial attitude. There will be that reconciliation at the end of the book, but that isn't really presented as them being proven wrong, more as Fleur showing an unexpected side. Which isn't actually unexpected to the readers which remember her from book four. But yes, Harry is the one who has the best and most justified attitude towards her (no wonder, he's the one who knows her best apart from Bill).

She's a bigot, yes, certainly. But personally I'm not losing all sympathy for her here. Snape's oath seems to have lessened her worries about Draco greatly, but she still must be fearing for him, while he is clearly still quite confident at this point about it, and trying to escape her protectiveness. Someone as proud as Narcissa is always going to show her worst side in a confrontation like that one, she has a reputation to uphold, and of course Harry does hit her rather hard with the Lucius comments, probably harder than he realizes because he doesn't know about her fears Voldemort might kill or otherwise punish Lucius for his failure.

It's interesting that Molly never brings up the matter of Harry having given them the initial loan, which Ron supposedly told her in a letter during book five. And she seems to have come to terms with it. It is an awesome scene ("Mr. Weasley and Mr. Weasley" is great), but I can't agree we've been led to believe that they were screw ups. Every time we've seen them, or very nearly, they were confident, capable and in control of the situation.

Yeah, Harry is like a broken clock that way.